The invention is directed to a push-button switch structure, particularly adapted for utilization in keyboards of typewriters and similar devices, for example teleprinter machines and data terminals, etc. The switch is provided with an actuating member which, upon actuation of the manual engageable key structure, is movable in opposition to the force of a helical spring extending between a portion of the housing structure for such a key and a seating surface on the actuating member of the switch, from an idle rest position into the working or actuated position, in which the spring forms the movable contact element and is brought into engagement with a cooperable stationary contact element upon movement of the actuating member.
A key structure utilizing a manually actuatable push button which is attached to the actuating member of a switch structure is already known, in which such push-bottom is arranged to be actuatable between an idle rest position and a working position, and utilizes a compression spring by means of which the push-button is returned from the working position into the rest position. U.S. Pat. No. 4,092,503 which corresponds to German OS No. 2,657,783 illustrate a push button switch of this type. In such known switch, the compression spring is provided with a longitudinally extended projection which, upon actuation, is brought into cooperative engagement with a counter-contact element. Such known switch has the disadvantage that, upon contacting engagement, the longitudinally extending projection stiffly or solidly strikes the cooperable counter-contact, with the possible production of contact chatter. As a result the cooperable counter-contact must be of a resilient type of construction. Such a push-button switch also is limited with respect to minimum height, as a result of the longitudinally extended projection, placing restrictions on the reduction in height of the key structure. Further, a relatively large number of component parts are required which in turn results in a more complicated structure and renders assembly more difficult.
Another example of a push-button switch utilizing a resilient spring member both as the contacting element as well as the biasing means for button returning means is illustrated in U.S. Pat. No. 3,842,230.